Thin film transistor-liquid crystal displays (TFT-LCDs) are widely used in various fields of production and living and use an M*N pixel matrix to display by progressive scanning. During the process of displaying, the TFT-LCD drives each pixel in the display panel to display by driving circuits. The driving circuits of a TFT-LCD mainly include a gate driving circuit and a data driving circuit. The data driving circuit is used to sequentially latch the input data in accordance with the timing of a clock signal, convert the latched data into analog signals, and input the analog signals to the data lines of the display panel. The gate driving circuit is typically implemented with shift registers, and the shift registers convert a clock signal into on/off voltages and output them to the gate lines of the display panel respectively. Each of the gate lines of the display panel is typically coupled with one shift register (i.e., the shift register in one stage). Pixels in the display panel are progressively scanned by the shift registers which output turn-on voltages in turn.
In the field of display, in order to continuously improve display effect and user experience, the displays having high definition and high number of pixels (Pixels Per Inch, PPI for short) have become a hot research topic. However, as the number of pixels increases, the number of pixels driven by a gate line in each row also increases and the load on the shift register increases. Therefore, it is necessary to improve the driving ability of the shift register.